Use os.path.realpath when tracking the cwd

[• rafael]

Summary

This is needed by TestCases/Posix/coverage-direct.cc

The problem is that the test does:

mkdir <dir>
cd <dir>
cd ..
rm -rf <dir>
<more commands>

the current directory currently looks like "/.../<dir>/../" which doesn't exist when dir is deleted.

at some point we should probably switch to using the os current directory (specially if we want to add subshell), but this is a small incremental improvement.

[rnk]

lgtm

utils/lit/lit/TestRunner.py

if cmd.commands[0].args[0] == 'cd':
             raise ValueError("'cd' cannot be part of a pipeline")
         if len(cmd.commands[0].args) != 2:
             raise ValueError("'cd' supports only one argument")
         newdir = cmd.commands[0].args[1]
         # Update the cwd in the parent environment.
         if os.path.isabs(newdir):
             shenv.cwd = newdir
         else:
-            shenv.cwd = os.path.join(shenv.cwd, newdir)
+            shenv.cwd = os.path.realpath(os.path.join(shenv.cwd, newdir))
         # The cd builtin always succeeds. If the directory does not exist, the
         # following Popen calls will fail instead.
         return 0
 
     procs = []
     input = subprocess.PIPE
     stderrTempFiles = []
     opened_files = []